1. Field of the Invention
The present invention relates generally to exhaust gas recirculation (EGR) systems, and more particularly, to an EGR valve integrated into a turbocharger with a valve inlet cast into the turbine housing and an actuation system mounted directly to the turbocharger.
2. Description of the Prior Art
Commercial Diesel EGR Systems require an EGR valve to control the flow of exhaust gas into the intake manifold. Commercial Diesel EGR Systems are characterized by very challenging packaging constraints of the EGR system, within the existing vehicle envelope, sensitivity to EGR system pressure losses and fuel consumption.
Present EGR systems are typically configured using separate components for each element of the system. This approach does not allow optimization of the system to accommodate the challenges described.
The present invention addresses the packaging and EGR system pressure loss resulting in a minimized effect on the vehicle fuel consumption. An EGR valve is incorporated onto a turbocharger turbine housing in a more compact manner than a separate EGR valve assembly (which is more typical within the component suppliers). In addition, the EGR valve is located such that the EGR system pressure losses are minimized (relative to the EGR valve). This is accomplished by taking advantage of the dynamic pressure associated with the turbine inlet flow. The design of the EGR valve integration provides xe2x80x9cinfinitexe2x80x9d flexibility in the orientation of the EGR valve outlet relative to the turbocharger centerline. This feature aids significantly in the packaging of the EGR system within the vehicle installation constraints. The design of the EGR valve lends itself to this packaging advantage. The invention employs a xe2x80x9cswing valvexe2x80x9d design. A EGR port is cast into the turbocharger turbine housing such that the gas dynamics of the engine exhaust entering the turbine housing supplements the flow of exhaust gas into the EGR system therefore reducing the EGR system pressure losses. The EGR valve is attached to the turbine housing such that the exhaust port from the EGR valve may be directed in an infinite number of directions without redesign of the turbocharger, turbine housing, or EGR valve sub-assembly.
The EGR valve actuator, and associated actuator mounting bracket are combined as a sub-assembly for mounting to the turbocharger permitting the EGR valve exhaust port to be directed in the best orientation for the EGR System/engine packaging.